Overall purposes of the proposed secondary data analysis (SDA) are to use social cognitive theory: 1) to assess the effectiveness of a cognitive behavioral antiretroviral (ART) adherence intervention in persons with past or current substance use, and 2) to understand the psychological variables affecting ART adherence behavior in persons with HIV/AIDS and past or current substance use. Primary aims are: 1) to compare the baseline ART adherence of HIV-infected persons who are and are not substance users, and 2) to compare the effect of the parent study's cognitive-behavioral ART adherence intervention with usual care on the ART adherence of HIV-infected persons who are substance users. The secondary aim is to explore if self-efficacy mediates the effects of social support, depression, and personality characteristics on the ART adherence of HIV-infected substance users. Multiple linear regression, repeated measures analysis, and path analysis will be used to evaluate each of the aims, respectively. Findings will be applicable to the design of specialized ART adherence interventions for this vulnerable population, thus leading to decreased HIV-related morbidity and delayed mortality, lower healthcare costs, and a reduced public health risk of resistant strains of HIV. [unreadable] [unreadable]